GMR versus differential coils in velocity induced eddy current testing

Ramos, Helena G.; Rocha, Tiago; Ribeiro, A. Lopes; Pasadas, Dário J.

doi:10.1109/i2mtc.2014.6860875

Cited by 7 publications

(4 citation statements)

References 13 publications

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“…GMR sensors have been used in eddy current testing to measure the depth of cracks in the structure of airplanes by Pasadas et al [ 100 ]. A high-density magnetic field is applied to the entire cracked structure.…”

Section: Application Of Gmr Sensors In Hybrid Eddy Current Testingmentioning

confidence: 99%

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

Rifai

Abdalla

Ali

et al. 2016

Sensors

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Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

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Section: Application Of Gmr Sensors In Hybrid Eddy Current Testingmentioning

confidence: 99%

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

Rifai

Abdalla

Ali

et al. 2016

Sensors

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“…25 Many researchers have performed investigations to prove that ECs can be used to measure the dimensions of near-surface defects (their depth, length, etc.). [27][28][29][30][31][32][33][34][35][36] Some researchers have also conducted studies attempting to measure defects within rail materials with the EC method. 26,33,34 However, in most of these studies, artificial defects have been used to prove the accuracy of EC testing in measuring defects.…”

Section: Eddy Current Testingmentioning

confidence: 99%

Limitations of eddy current inspection for the characterization of near-surface cracks in railheads

Anandika

Lundberg

2021

Proceedings of the Institution of Mechanical Engineers, Part F:

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Eddy current (EC) testing is the most commonly used method to inspect near-surface cracks in railheads. Monitoring surface defects periodically is important to assess the track quality for serving daily operations. Nevertheless, despite being used in many countries, this method has limitations when characterizing cracks under the rail surface. Theoretically, EC testing is unreliable for the inspection of many cracks situated too close to each other in a concentrated location. This study has aimed to prove these limitations. EC signals from inspected cracks were compared with real crack profile parameters, i.e. depth and area, which were delivered by slicing the inspected cracked spots into 0.65 mm-thick pieces. The results show that the EC signal responses to the parameters of area and depth may lead to misleading measurements of the near-surface crack depth in the railhead. For instance, a shallower crack with a larger area can generate a higher EC signal response than a deeper crack with a smaller area. Another important conclusion is that the EC testing in this experiment could not be used to measure densely located cracks, which are those near-surface cracks which are typically found in a rail track.

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“…All these applications have in common that they involve mechanical systems that obey eigenfrequencies and the tendency to oscillate even though intended or parasitic in form of undesired vibrations of laboratory setups. A typical example of the latter was observed in [31]. The time-dependent velocity accounts for a more intricate eddy currents profile inside the conductor.…”

Section: Introductionmentioning

confidence: 96%

Oscillatory Motion of Permanent Magnets Above a Conducting Slab

et al. 2015

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This paper provides the 3-D time-dependent analytical solution of the electromagnetic fields and forces emerging if a coil or a permanent magnet moves with a sinusoidal velocity profile relative to a conducting slab of finite thickness. The results can be readily used in application scenarios related to electromagnetic damping, eddy current braking, energy harvesting, or nondestructive testing in order to efficiently analyze diffusion and advection processes in case of harmonic motion. This paper is performed for rectangular and circular coils as well as for cuboidal and cylindrical permanent magnets. The back reaction of the conductor and therewith associated inductive effects are considered. The solutions of the governing equations and the integral expressions for the time-dependent drag and lift force are provided. The analytical results are verified by a comparison with numerical simulations obtained by the finite-element method. The relative difference between the analytically and numerically evaluated force profiles was <0.1%. Exemplary calculations show that the waveforms of both force components strongly depend on the level of constant nominal velocity v 0 , the magnitude of the velocity oscillation amplitude v 1 , and the underlying oscillation frequency f v .Index Terms-Analytical models, boundary value problems, eddy currents, harmonic analysis, permanent magnets. 0018-9464

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GMR versus differential coils in velocity induced eddy current testing

Cited by 7 publications

References 13 publications

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

Limitations of eddy current inspection for the characterization of near-surface cracks in railheads

Oscillatory Motion of Permanent Magnets Above a Conducting Slab

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